Size estimates

bearkatjen

I've never really put much stock into third trimester size estimates from ultrasounds, because it seems like they have a reputation for being off.

I had a ultrasound at 30 weeks yesterday, and my OB and I discussed the baby's size, and compared DS1's size during my third trimester with him.

I had always assumed DS1 was estimated average during third tri, and then born much smaller than that, but according to my records, through out my third trimester with him, he actually measured small, and kept moving down on the percentile chart. So, he was smaller than predicted at birth, but the general estimation that I was carrying a small baby was right on the money. I had pre-e with him, and my OB said that could have played a part in his size.

Well my current pregnancy is going great, stellar BP, and the baby is measuring quite a bit more than DS. He is in the 60th percentile, so a nice average size, and more in line with what DH and I were at birth.

For the first time, I'm feeling like this is a very different pregnancy and baby than my first, but I'm also wondering how much stalk I should put into the size estimates. I don't expect them to be right on the money, but do you think it's safe to assume I'm having an average size baby?

If you're a STM, how far off were your size estimates?

Do you think it's more common for the estimates to be high or low? 

mrsodonnell12

I will refuse any sizing u/s since they can be (I believe) + or - 2 pounds. I wouldnt put any stock into it really.

I had a friend who had a baby about 6 months ago and her OB was pushing for a scheduled c-section because baby was measuring over 12 pounds on the u/s.... baby was born 2 days past his due date and weighed 9 lbs. I think its ridiculous that an OB would push for a major surgery based on medical equipment that is not accurate when it comes to weight. It scared my friend. I am just so happy she felt strongly enough about wanting a natural birth to decline the c-section and go into labor on her own.

g8trkim

I've definitely heard people say their estimates were way off. I think there are a lot of factors that play a part. The 30 week u/s is early in the 3rd tri, so even if baby is measuring a certain percentile then they could grow quickly or slowly after that. DS measured 65% at 30 weeks and was born a week early at 7lbs 12oz so pretty in line with the u/s. The last weeks leading up to his birth my doctors would estimate based on feeling my stomach, and they were spot on. When I was in labor, she estimated he was 7 1/2 - 8lbs. This baby measured 75% at 30 weeks, and my docs seem to think she's a little bigger than DS, probably in the high average range (so over 8lbs but not huge). We'll see soon enough.

Nericole

I've heard that these can be off, but they wouldn't do them at all if they were ALWAYS off, you know what I mean? We had an ultrasound a week ago for sizing, baby's measuring small, so we're having another done in a week. I believe that the weight is pretty close, considering my size, and what my midwife says when she palpates my belly. My friend's baby is 8 weeks old now, and on the day before her c-section, they measured him to be 8 pounds 15 ounces. He was born at 8 pounds 14 ounces. Which is pretty darn close, if you ask me.

MelleTX

With twins, I get a growth ultrasound every 4 weeks. The measurements are just estimates, but since they are done by the same DR on the same machine, I feel like we get to see a good pattern of growth which is really what I am looking at. 

Are they both really 4lbs right now? Maybe, maybe not. That seems high to me. But, they have been very consistently at the tope of the range for their gestational age this entire pregnancy so I know they are growing properly and proportionately.  

minervacullen

I never had a sizing u/s, but my old OB would feel baby and push on my tummy. He would guess that way. He guessed 8lbs 6oz and DS was 8lbs 8oz. So maybe going old school is more accurate. He was pretty old, I liked that about him though.

mrsodonnell12

MelleTX:

With twins, I get a growth ultrasound every 4 weeks. The measurements are just estimates, but since they are done by the same DR on the same machine, I feel like we get to see a good pattern of growth which is really what I am looking at. 

Are they both really 4lbs right now? Maybe, maybe not. That seems high to me. But, they have been very consistently at the tope of the range for their gestational age this entire pregnancy so I know they are growing properly and proportionately.  

See I think using an u/s to track growth is different than doing one u/s at 36 weeks and saying your baby weighs 10 pounds time for a c-section. I think teh same goes for measuring fundal height..... they are necessarily looking for big baby vs little baby when they do that, they are looking for consistent growth. If the growth changes drastically in either direction it is a warning sign that something is going on. I think there are legit reasons for using the technology, but to say oh this baby is for sure 10 pounds based on an u/s we just did is a crock.

mrsodonnell12

b0710:

minervacullen:

I never had a sizing u/s, but my old OB would feel baby and push on my tummy. He would guess that way. He guessed 8lbs 6oz and DS was 8lbs 8oz. So maybe going old school is more accurate. He was pretty old, I liked that about him though.

 That is cool.  My doctor was actually way closer too.  He predicted a 7 - 71/2 lb baby and my sone was 7 lb 2 oz.  It was the ultrasound that was 2 pounds heavy  

My midwife did the same thing with DS and she was very close. With taht siad, most babies are in the 7 lb range so its not really something I would bank on

shibby00

I had an us with DD about 5 days before she was born. It said 7lbs 1oz, and she was 7lbs 10ozs at birth. So it was pretty close.

mw_sorrel

With DS I had a bp scan at 38 weeks and he was estimated to be 8 lbs. 12 oz. I was induced for medical reasons at 39 weeks and he was 9 lbs. even.

rlyttle

Mine was pretty much right on. They told me he was going to be long, he was 21", and they told me he was 7lbs at the time. He was born one week later at 7lbs 6oz.

albjag

I had regular growth scans/BPPs d/t GD

Latest estimate at 39 wks was 9lbs2oz

birthweight: 8lb6oz 

MTNurse

I had a growth u/s at 38 weeks with DS and it estimated him at 10# 3oz. He was born at 39w5d and was 11#. I believed my doctor (who also thought he was a big baby by feeling him) and the u/s and decided to go with a c-section. I don't regret listening to my doctor one bit!

LisaKF3

Unless this baby makes her appearance before Monday, they have me scheduled for a growth ultrasound at 41w!  Can't wait to hear this estimate

bgf1

I was told that my son would be small but healthy under seven pounds. He was born at 38 weeks and was 7lbs 11 oz.

MamaG1231

My doctor doesn't do size estimates.  I specifically asked for one today because I finally got to see my delivering dr from last time.  He was the only one that ever even mentioned that I'd have a big baby last time.  And that was 2 hrs before he was born.

 The only size measurements my dr does is the uterus.  Which is always on point.  With this pregnancy and last.  But last time I had a 10lb 9oz baby.  So i asked the dr today and included in my internal exam - he gave me his best guess that this baby is over 10lbs also.

I actually trust his experience more than I'd trust a U/S.

blue1981

I really hope you guys are right. The ultrasound place says they can be off by up to 15% in either direction but I had an ultrasound yesterday at 32 weeks and 1 day and my baby is measuring overall in the 90th percentile but on the size of his head he is in the 95th percentile and his stomach is in the 99.9th percentile. Its his short femur that brings him down a little bit. they estimated his weight to be at 5.5 lbs already which is enormous and made me a bit nervous. I am hoping it is an overestimate. I am only 5'4 and was 110 pounds before pregnancy so this is a pretty big baby for me lol!

Kingston54

I would only listen to their estimate at the very end.  My OB was very accurate when guessing - within ounces!  But that was at my 38 or 39 week appointment.